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| 2. |
- Bärgman, Jonas, 1972, et al.
(författare)
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On data security and analysis platforms for analysis of naturalistic driving data
- 2011
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Ingår i: Proceedings of the 8th European Congress and Exhibition on Intelligent Transport Systems and Services, June 2011, Lyon.
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Konferensbidrag (refereegranskat)abstract
- Studies involving naturalistic driving data, of which Naturalistic Field Operational Tests (N-FOTs) are a subset, are becoming increasingly important for understanding the factors influencing accident causation as well as for the development and evaluation of active safety systems. The methodology project FESTA developed a handbook on how to plan and implement FOTs. This handbook has been extensively used as a guideline in the euroFOT project. However, “the devil is in the details” when implementing e.g. the platforms for data security and analysis in projects which deal with analysis of large amounts of sensitive naturalistic driving data, such as euroFOT. That is, although a guideline such as FESTA is used, how the details are implemented is what makes the implementation a success or not. This paper is a case description of the implementation of the data security and analysis platform used for euroFOT (and other naturalistic data projects) at the SAFER Vehicle and Traffic Safety Centre. The paper covers aspects ranging from physical access to analysis rooms and corresponding digital access, via the platforms for pre-processing of data, to the platforms for information extraction for hypothesis analysis and statistics. The considerations in the design and choice of these platforms include subjects (drivers) privacy concerns, industry commercial concerns, as well as the needs and requirements from the analysis.
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| 3. |
- Schepers, Paul, et al.
(författare)
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The development of cycling in european countries since 1990
- 2021
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Ingår i: European Journal of Transport and Infrastructure Research. - : TU Delft. - 1567-7141 .- 1567-7133. ; 21:2, s. 41-70
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Tidskriftsartikel (refereegranskat)abstract
- High pre-World-War-2 modal shares of cycling in European countries sharply decreased during the post-war decades. In the 1990s, European governments introduced policies to increase bicycle use. However, a database or longitudinal study on the development of bicycle use in European countries is lacking. The goal of this paper is to examine to what degree the amount of cycling has increased over the past decades, also in the context of potentially competing modes. Distances travelled per capita according to National Travel Surveys have been collected and were aggregated to seven 4-year periods between 1990 and 2017. Multilevel regression analyses on distance travelled per capita by bicycle, on foot, by public transport, and by passenger car were conducted for all countries. Additionally, analyses were conducted for which the 14 countries with data on bicycle use were divided in three groups categorised according to distance cycled per capita at the beginning of the study period. Distance cycled per capita per year ranged from some 30 km to 900 km. The results of all four regression analyses suggested that distance cycled per capita remained fairly constant over the past decades. Germany is an exception with some 150 km per capita more, in relative terms a 50% increase. Geographical variation in development is evidenced by a substantial increase of distance cycled per inhabitant in the capital cities of the countries included in the study. The outcomes suggest distance travelled on foot and by public transport (bus, tram, and metro) also remained fairly constant while the distance travelled by car increased by about 10% during the study period. We did not find indications that cycling substitutes travel on foot, by public transport or by car.
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| 4. |
- Victor, Trent, 1968, et al.
(författare)
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Analysis of Naturalistic Driving Study Data: Safer Glances, Driver Inattention, and Crash Risk
- 2014
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- This work was sponsored by the secondStrategic Highway Research Program (SHRP 2), which isadministered by the Transportation Research Board of the National Academies. This project wasmanaged by Ken Campbell, Chief Program Officer for SHRP 2 Safety, and Jim Hedlund,SHRP 2SafetyCoordinator.The research reported on herein was performed by the main contractor SAFER Vehicle and TrafficSafety Centre at Chalmers, Gothenburg, Sweden. SAFER is a joint research unit where 25 partnersfrom the Swedish automotive industry, academia and authoritiescooperate to make a center ofexcellence within the field of vehicle and traffic safety (seewww.chalmers.se/safer). The host andlegal entity SAFER is Chalmers University of Technology. Principle Investigator Trent Victor is AdjunctProfessor at Chalmers and worked on the project as borrowed personnel to Chalmers but his mainemployer is Volvo Cars. The other authors of this report are Co-PI Marco Dozza, Jonas Bärgman, andChristian-Nils Boda of Chalmers University of Technology(as a SAFER partner); Johan EngströmandGustav Markkulaof Volvo Group Trucks Technology(as a SAFER partner); John D. Lee of Universityof Wisconsin-Madison (as a consultant to SAFER); and Carol Flannagan of University of MichiganTransportation Research Institute (UMTRI) (as a consultant to SAFER). The authors acknowledge thecontributions to this research from Ines Heinig, Vera Lisovskaja, Olle Nerman, Holger Rootzén,Dmitrii Zholud, Helena Gellerman, Leyla Vujić, Martin Rensfeldt,Stefan Venbrant, Akhil Krishnan,Bharat Mohan Redrouthu, Daniel Nilssonof Chalmers; Mikael Ljung-Aust of Volvo Cars; Erwin Boer;Christer Ahlström and Omar Bagdadi of VTI.
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| 5. |
- Arikere, Adithya, 1987, et al.
(författare)
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On the Potential of Accelerating an Electrified Lead Vehicle to Mitigate Rear-End Collisions
- 2015
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Ingår i: Proceedings of the 3rd International Symposium on Future Active Safety Technology Towards zero traffic accidents, 2015. ; , s. 377-384
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Konferensbidrag (refereegranskat)abstract
- This paper analyzes the potential safety benefit from autonomous acceleration of an electrified lead vehicle to mitigate or prevent being struck from behind. Safety benefit was estimated based on the expected reduction in relative velocity at impact in combination with injury risk curves. Potential issues and safety concerns with the operation and implementation of such a system in the real world are discussed from an engineering and human factors stand point. In particular, the effect of the pre-collision acceleration in reducing whiplash injury risk due to change in head posture and reduction of crash severity is also discussed. In general, this study found that autonomously accelerating an electrified lead vehicle can mitigate and prevent rear-end collisions and significantly increase the safety benefits from existing systems such as autonomous emergency braking.
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| 6. |
- Bálint, András, 1982, et al.
(författare)
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Multitasking additional-to-driving: Prevalence, structure, and associated risk in SHRP2 naturalistic driving data
- 2020
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Ingår i: Accident Analysis and Prevention. - : Elsevier BV. - 0001-4575. ; 137
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Tidskriftsartikel (refereegranskat)abstract
- Objective This paper 1) analyzes the extent to which drivers engage in multitasking additional-to-driving (MAD) under various conditions, 2) specifies odds ratios (ORs) of crashing associated with MAD, and 3) explores the structure of MAD. Methods Data from the Second Strategic Highway Research Program Naturalistic Driving Study (SHRP2 NDS) was analyzed to quantify the prevalence of MAD in normal driving as well as in safety-critical events of various severity level and compute point estimates and confidence intervals for the corresponding odds ratios estimating the risk associated with MAD compared to no task engagement. Sensitivity analysis in which secondary tasks were re-defined by grouping similar tasks was performed to investigate the extent to which ORs are affected by the specific task definitions in SHRP2. A novel visual representation of multitasking was developed to show which secondary tasks co-occur frequently and which ones do not. Results MAD occurs in 11 % of control driving segments, 22 % of crashes and near-crashes (CNC), 26 % of Level 1–3 crashes and 39 % of rear-end striking crashes, and 9 %, 16 %, 17 % and 28 % respectively for the same event types if MAD is defined in terms of general task groups. The most common co-occurrences of secondary tasks vary substantially among event types; for example, “Passenger in adjacent seat – interaction” and “Other non-specific internal eye glance” tend to co-occur in CNC but tend not to co-occur in control driving segments. The odds ratios of MAD using SHRP2 task definitions compared to driving without any secondary task and the corresponding 95 % confidence intervals are 2.38 (2.17–2.61) for CNC, 3.72 (3.11–4.45) for Level 1–3 crashes and 8.48 (5.11–14.07) for rear-end striking crashes. The corresponding ORs using general task groups to define MAD are slightly lower at 2.00 (1.80–2.21) for CNC, 3.03 (2.48–3.69) for Level 1–3 crashes and 6.94 (4.04–11.94) for rear-end striking crashes. Conclusions The number of secondary tasks that the drivers were engaged in differs substantially for different event types. A graphical representation was presented that allows mapping task prevalence and co-occurrence within an event type as well as a comparison between different event types. The ORs of MAD indicate an elevated risk for all safety-critical events, with the greatest increase in the risk of rear-end striking crashes. The results are similar independently of whether secondary tasks are defined according to SHRP2 or general task groups. The results confirm that the reduction of driving performance from MAD observed in simulator studies is manifested in real-world crashes as well.
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| 7. |
- Bärgman, Jonas, 1972, et al.
(författare)
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Counterfactual simulations applied to SHRP2 crashes: The effect of driver behavior models on safety benefit estimations of intelligent safety systems
- 2017
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Ingår i: Accident Analysis and Prevention. - : Elsevier BV. - 0001-4575. ; 102, s. 165-180
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Tidskriftsartikel (refereegranskat)abstract
- As the development and deployment of in-vehicle intelligent safety systems (ISS) for crash avoidance and mitigation have rapidly increased in the last decades, the need to evaluate their prospective safety benefits before introduction has never been higher. Counterfactual simulations using relevant mathematical models (for vehicle dynamics, sensors, the environment, ISS algorithms, and models of driver behavior) have been identified as having high potential. However, although most of these models are relatively mature, models of driver behavior in the critical seconds before a crash are still relatively immature. There are also large conceptual differences between different driver models. The objective of this paper is, firstly, to demonstrate the importance of the choice of driver model when counterfactual simulations are used to evaluate two ISS: Forward collision warning (FCW), and autonomous emergency braking (AEB). Secondly, the paper demonstrates how counterfactual simulations can be used to perform sensitivity analyses on parameter settings, both for driver behavior and ISS algorithms. Finally, the paper evaluates the effect of the choice of glance distribution in the driver behavior model on the safety benefit estimation. The paper uses pre-crash kinematics and driver behavior from 34 rear-end crashes from the SHRP2 naturalistic driving study for the demonstrations. The results for FCW show a large difference in the percent of avoided crashes between conceptually different models of driver behavior, while differences were small for conceptually similar models. As expected, the choice of model of driver behavior did not affect AEB benefit much. Based on our results, researchers and others who aim to evaluate ISS with the driver in the loop through counterfactual simulations should be sure to make deliberate and well-grounded choices of driver models: the choice of model matters.
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| 8. |
- Bärgman, Jonas, 1972, et al.
(författare)
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How does glance behavior influence crash and injury risk? A ‘what-if’ counterfactual simulation using crashes and near-crashes from SHRP2
- 2015
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Ingår i: Transportation Research Part F: Traffic Psychology and Behaviour. - : Elsevier BV. - 1369-8478. ; 35, s. 152-169
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Tidskriftsartikel (refereegranskat)abstract
- As naturalistic driving data become increasingly available, new analyses are revealing the significance of drivers’ glance behavior in traffic crashes. Due to the rarity of crashes, even in the largest naturalistic datasets, near-crashes are often included in the analyses and used as surrogates for crashes. However, to date we lack a method to assess the extent to which driver glance behavior influences crash and injury risk across both crashes and near-crashes. This paper presents a novel method for estimating crash and injury risk from off-road glance behavior for crashes and near-crashes alike; this method can also be used to evaluate the safety impact of secondary tasks (such as tuning the radio). We apply a ‘what-if’ (counterfactual) simulation to 37 lead-vehicle crashes and 186 lead-vehicle near-crashes from lead-vehicle scenarios identified in the SHRP2 naturalistic driving data. The simulation combines the kinematics of the two conflicting vehicles with a model of driver glance behavior to estimate two probabilities: (1) that each event becomes a crash, and (2) that each event causes a specific level of injury. The usefulness of the method is demonstrated by comparing the crash and injury risk of normal driving with the risks of driving while performing one of three secondary tasks: the Rockwell radio-tuning task and two hypothetical tasks. Alternative applications of the method and its metrics are also discussed. The method presented in this paper can guide the design of safer driver–vehicle interfaces by showing the best tradeoff between the percent of glances that are on-road, the distribution of off-road glances, and the total task time for different tasks.
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| 9. |
- Chiari, Lorenzo, et al.
(författare)
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Audio-biofeedback for balance improvement: an accelerometry-based system.
- 2005
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Ingår i: IEEE Transactions on Biomedical Engineering. - 0018-9294 .- 1558-2531. ; 52:12, s. 2108-11
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Tidskriftsartikel (refereegranskat)abstract
- This paper introduces a prototype audio-biofeedback system for balance improvement through the sonification using trunk kinematic information. In tests of this system, normal healthy subjects performed several trials in which they stood quietly in three sensory conditions while wearing an accelerometric sensory unit and headphones. The audio-biofeedback system converted in real-time the two-dimensional horizontal trunk accelerations into a stereo sound by modulating its frequency, level, and left/right balance. Preliminary results showed that subjects improved balance using this audio-biofeedback system and that this improvement was greater the more that balance was challenged by absent or unreliable sensory cues. In addition, high correlations were found between the center of pressure displacement and trunk acceleration, suggesting accelerometers may be useful for quantifying standing balance.
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| 10. |
- Dozza, Marco, 1978, et al.
(författare)
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A data-driven framework for the safe integration of micro-mobility into the transport system: Comparing bicycles and e-scooters in field trials
- 2022
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Ingår i: Journal of Safety Research. - : Elsevier BV. - 0022-4375. ; 81, s. 67-77
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Tidskriftsartikel (refereegranskat)abstract
- Introduction : Recent advances in technology create new opportunities for micro-mobility solutions even as they pose new challenges to transport safety. For instance, in the last few years, e-scooters have become increasingly popular in several cities worldwide; however, in many cases, the municipalities were simply unprepared for the new competition for urban space between traditional road users and e-scooters, so that bans became a necessary, albeit drastic, solution. In many countries, traditional vehicles (such as bicycles) may not be intrinsically safer than e-scooters but are considered less of a safety threat, possibly because—for cyclists—social norms, traffic regulations, and access to infrastructure are established, reducing the number of negative stakeholders. Understanding e-scooter kinematics and e-scooterist behavior may help resolve conflicts among road users, by favoring a data-driven integration of these new e-vehicles into the transport system. In fact, regulations and solutions supported by data are more likely to be acceptable and effective for all stakeholders. As new personal-mobility solutions enter the market, e-scooters may just be the beginning of a micro-mobility revolution. Method : This paper introduces a framework (including planning, execution, analysis, and modeling) for a data-driven evaluation of micro-mobility vehicles. The framework leverages our experience assessing bicycle dynamics in real traffic to make objective and subjective comparisons across different micro-mobility solutions. In this paper, we use the framework to compare bicycles and e-scooters in field tests. Results : The preliminary results show that e-scooters may be more maneuverable and comfortable than bicycles, although the former require longer braking distances. Practical Applications : Data collected from e-scooters may, in the short term, facilitate policy making, geo-fencing solutions, and education; in the long run, the same data will promote the integration of e-scooters into a cooperative transport system in which connected automated vehicles share the urban space with micro-mobility vehicles. Finally, the framework and the models presented in this paper may serve as a reference for the future assessment of new micro-mobility vehicles and their users’ behavior (although advances in technology and novel micro-mobility solutions will inevitably require some adjustments).
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